How stress affects the human brain 1/27/25 HPA-Axis HPA = Hypothalamic-Pituitary-Adrenal Exercise and meditation help genes function optimally. Hippocampus Shrinkage (what causes it) - Long term stress - Untreated depression - Obesity - Lack of exercise - Junk food (food high in sugar and fat) - Concussions - Alcohol consumption Simon LeVay - Gay man - Success full research on the brain (1991) - The INAH3 of homosexual men and heterosexual women is about half the size of the INAH3 of heterosexual men INAH3 = 3rd interstitial nucleus of the anterior hypothalamus. Biological Perspective on Behavior - Should psychologists use the term mental illness? Mental Illness versus Brain Illness - How does therapy work? o By changing the brain - Do you think that there are brain differences between those who believe in god and those who are atheists or between conservatives and liberals? Religious People Vs. Atheists - January 16, 2012, Scientific American Mind article - When religious people think about God, the same parts of their brain are active as when they are thinking about real objects (God is real to them) o On average, religious people have: Larger frontal lobes .. Conservatives versus Liberals - Conservatives have a larger amygdala, which is a part of the brain that is sensitive to threats and active when we are anxious. - This may be one reason why conservatives rate highly the importance of controlling our borders and funding our military. Neuroplasticity - Neuro – refers to the nervous system - Plasticity – refers to the ability to be molded or changed Neuroplasticity is the brain’s ability to change based on experience. The brain is like a muscle if you exercise it, it will develop. This means that your intelligence isn’t fixed – Fixed versus Growth Mindset Carol Dweck – Stanford Univ Psychologists Studying the Brain - Anatomy (structure) - Electrical Activity - Chemistry Anatomical Approach - What are the parts of the brain and what are their functions (what do they do) - The brain wasn’t always considered the organ of behavior o Memorize it by brain o I’m broken-brained (sadness) - Direct brain observation o Brains of the Month Club Anatomical Approach 4 step Procedure - Study behavior (that you are interested in) - Destroy brain tissue (that you believe may be involved in the behavior) - Reevaluate behavior (did destruction of the brain tissue cause a change in behavior) - Histology (microscopic analysis of brain tissue to determine the degree of destruction accomplished in step 2) What are some of the reasons why behavior might NOT appear to change following a brain injury? 1. Looking at the wrong behavior 2. Not enough brain tissue was destroyed 3. Part of a system 4. Fixing the brain (drugs, surgery, DBS, etc.) 5. Compensatory strategies 6. Individual differences 7. Neural compensations 8. Brain self-repair (neurogenesis, new connections between neurons, new pathways) 1/29/25 Pruning and Neuro compensation - Following birth, the number of synapses greatly expands until about age two and then begins to decline. Some neurons that don’t get used will be dead. Neurons that fire together wire together (they are still healthy) With brain damage early in life, fewer neurons will die, so some neurons that normally would have died can take over some of the functions of damaged brain areas. This is an example of neural compensation ASD = Less Pruning of Synapses An example of a Compensatory Strategy & Neuroplasticity - Echolocating by blind people. - A small number of blind people emit sounds (like bats do) and then listen for the echo to get information about objects in the environment - Some blind people become excellent at this and can hike, bike, and play basketball - One man was able to locate objects within 3 degrees. An example of Neuroplasticity - According to a blind echolocation expert, areas of the back of the brain that normally process visual information are now processing sound information (the echoes) Language gets processed in the left hemisphere of the brain. Psychosurgery - Moniz operated a large mental institution in Portugal. - While attending a conference, he learned that the behavior of a difficult-to-control chimpanzee was dramatically improved by destroying portions of her frontal lobes. Rose Mary Kennedy - Lobotomy at age 23 because she was difficult to control and intellectually impaired - The surgery left her permanently incapacitated History of Psychosurgery - Freeman performed an estimated 4,000 lobotomies and was the first to use an orbit class (ice pick) CAT Scan = computer axial tomography Or CT scan = computer tomography MRI (Magnetic Resonance Imaging) DTI (diffusion tensor imaging) Studying the brain - Anatomy (structure) - Electrical activity Brian Electrical Activity Recording - EEG – Electroencephalogram o Attention/level of alertness o Epilepsy (abnormal electrical activity) o Depth of anesthesia o 2013 – FDA approved the use of the EEG to help diagnose ADHD (attention deficit hyperactivity disorder). Certain combinations of Theta and Beta waves are more common in ADHD - MEG – magnetoencephalography o Electrical activity in neurons creates magnetic fields that the MEG can detect o MEG produces a very quick and precise picture of brain activity o It has GREATER SPATIAL RESOLUTION than the EEG o It is excellent at detecting (pinpointing) partial epilepsy - EP (evoked potential) or ERP (event-related potential) - Single-cell recording GAMMA Waves (Active Thought/learning) BETA Waves (alert) ALPHA Waved (relaxed) THETA Waves (Sleepy/light sleep) DELTA Waves (deep sleep) Brain Activity Converted to Text (2015) - Scientists reported that they were able to convert recordings from cortical cells of a person reading into text with 75%. “Typing” via Monitoring Single Neurons of the Motor Cortex - 2021 – paralyzed patients imagine writing letters as their motor cortex is monitored. - They achieved typing speeds of 90 characters per minute with 94% raw Brain Activity Converted to speech - The current rate of converted speech is 78 words per minute, while the average person speaks at 160 words per minute. - Before the brain’s impact, communication was much slower and done via head movements that activities individual letters.
